Increased interlayer adhesion of three-dimensional printed articles

ABSTRACT

Technologies are generally described to increase interlayer adhesion of a 3D printed article. A printhead of a 3D printing system may include an extrusion nozzle configured to deposit one or more polymer layers onto a substrate to form the 3D printed article. A microplasma source may be coupled to the extrusion nozzle and may be configured to treat a surface of the substrate or a surface of the deposited polymer layers with plasma from the microplasma. The plasma may include at least one reactive species that may oxidize the surface of the substrate or the surface of the deposited polymer layer upon treatment in order to increase the interlayer adhesion of the 3D printed article.

BACKGROUND

Unless otherwise indicated herein, the materials described in thissection are not prior art to the claims in this application and are notadmitted to be prior art by inclusion in this section.

While the first three-dimensional (3D) printed articles were generallymodels, the industry is quickly advancing by creating 3D printedarticles that may be functional parts in more complex systems, such ashinges, tools, and structural elements. Many of these parts may bear amechanical load, and the stronger the parts' load-bearing capabilities,the more generalized the parts' functional applications may be. Anarising mechanical challenge for more advanced 3D printed articles maybe delamination due to poor surface adhesion between layers of theformed 3D printed article, especially when plastics are used information.

Current attempts in 3D printing systems to solve such mechanical issuescould use improvements and/or alternative or additional solutions toincrease surface adhesion between the layers of the formed 3D printedarticle.

SUMMARY

The present disclosure generally describes methods, apparatuses,systems, devices, and/or computer program products employed to increaseinterlayer adhesion of a three-dimensional (3D) printed article.

According to some examples, methods are described to increase interlayeradhesion of a 3D printed article. An example method may includedepositing a polymer layer from an extrusion nozzle of a 3D printer ontoa substrate to form the 3D printed article, where the extrusion nozzleis coupled to a microplasma source. The example method may also includetreating a surface of the substrate or a surface of the depositedpolymer layer with plasma from the microplasma source.

According to other examples, printheads may be described. An exampleprinthead may include an extrusion nozzle configured to deposit one ormore polymer layers onto a substrate to form a 3D printed article. Theexample printhead may also include a microplasma source coupled to theextrusion nozzle, the microplasma source being configured to treat asurface of the substrate or a surface of the deposited polymer layerwith plasma from the microplasma source.

According to further examples, systems for increasing interlayeradhesion of a 3D printed article are described. An example system mayinclude a deposition module that includes an extrusion nozzle and isconfigured to deposit one or more polymer layers from the extrusionnozzle onto a substrate to form a 3D printed article. The example systemmay also include a treatment module including a microplasma sourcecoupled to the extrusion nozzle and configured to treat a surface of thesubstrate or a surface of the one or more deposited polymer layers withplasma from the microplasma source. The example system may furtherinclude a controller configured to coordinate operations of thedeposition module and the treatment module during a fabrication of the3D printed article.

According to yet further examples, a computer-readable storage mediumwith instructions stored thereon to increase interlayer adhesion of a 3Dprinted article may be described. The instructions may cause a method,similar to the methods provided above, to be performed when executed.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features of this disclosure will become morefully apparent from the following description and appended claims, takenin conjunction with the accompanying drawings. Understanding that thesedrawings depict only several embodiments in accordance with thedisclosure and are, therefore, not to be considered limiting of itsscope, the disclosure will be described with additional specificity anddetail through use of the accompanying drawings, in which:

FIGS. 1A and 1B illustrate example configurations of a printheademployed in a three-dimensional (3D) printing system to increaseinterlayer adhesion of a 3D printed article;

FIG. 2 illustrates an example comparison of surface adhesion of asubstrate with plasma treatment and a substrate without plasmatreatment;

FIGS. 3A and 3B illustrate examples of microplasma sources that may becoupled to an extrusion nozzle;

FIG. 4 illustrates another example of a microplasma source that may becoupled to an extrusion nozzle;

FIG. 5 illustrates an example system to increase interlayer adhesion ofa 3D printed article through employment of an extrusion nozzle coupledto a microplasma source;

FIG. 6 illustrates a general purpose computing device, which may be usedto facilitate an increase of interlayer adhesion of a 3D printed articlethrough employment of an extrusion nozzle coupled to a microplasmasource;

FIG. 7 is a flow diagram illustrating an example method to increaseinterlayer adhesion of a 3D printed article through employment of anextrusion nozzle coupled to a microplasma source that may be performedby a computing device such as the computing device in FIG. 6; and

FIG. 8 illustrates a block diagram of an example computer programproduct, all arranged in accordance with at least some embodimentsdescribed herein.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar articles, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented herein. The aspects of the present disclosure, as generallydescribed herein, and illustrated in the Figures, can be arranged,substituted, combined, separated, and designed in a wide variety ofdifferent configurations, all of which are explicitly contemplatedherein.

This disclosure is generally drawn, among other things, to methods,apparatuses, systems, devices, and/or computer program products relatedto an increase of interlayer adhesion of a 3D printed article.

Briefly stated, technologies are generally described to increaseinterlayer adhesion of a 3D printed article. A printhead of a 3Dprinting system may include an extrusion nozzle configured to depositone or more polymer layers onto a substrate to form the 3D printedarticle. A microplasma source may be coupled to the extrusion nozzle andmay be configured to treat a surface of the substrate or a surface of adeposited polymer layer with plasma from the microplasma source. Theplasma may include at least one reactive species that may oxidize thesurface of the substrate or the surface of the deposited polymer layerupon treatment in order to increase the interlayer adhesion of the 3Dprinted article.

FIGS. 1A and 1B illustrate example configurations of a printheademployed in a 3D printing system to increase interlayer adhesion of a 3Dprinted article, arranged in accordance with at least some embodimentsdescribed herein.

As shown in a diagram 100A, a printhead of a 3D printing system mayinclude an extrusion nozzle 110 and a microplasma source 104. Theextrusion nozzle 110 may be configured to deposit one or more polymerlayers onto a surface of a substrate 108 as illustrated by a path ofpolymer deposition 112. In some examples, the extrusion nozzle 110 maybe further configured to rotate as the polymer layer is deposited totrack changes in the polymer deposition. The microplasma source 104 maybe configured to treat 114 the surface of the substrate or treat thesurface of the one or more deposited polymer layers dependent on aposition of the microplasma source 104 relative to a position of theextrusion nozzle 110. The surfaces may be treated with a plasma drop 106from the microplasma source 104 in response to a voltage application toat least one of two electrodes positioned in the microplasma source 104.

In one embodiment, the microplasma source 104 may be positioned suchthat the plasma drop 106 precedes the path of polymer deposition 112from the extrusion nozzle 110 to treat 114 a surface of a substrate 108,as illustrated in configuration 102. In another embodiment, themicroplasma source 104 may be positioned such that the plasma drop 106follows the path of polymer deposition 112 from the extrusion nozzle 110to treat the surface of a previously deposited polymer layer, asillustrated in a configuration 120. For purposes, of this section, theconfiguration 102 may be referred to as a leading plasma configurationand the configuration 120 may be referred to as a trailing plasmaconfiguration.

As shown in a diagram 100B of FIG. 1B, an alternate configuration of theprinthead may include the microplasma source 104 incorporated with theextrusion nozzle 110 to cause the surface of the one or more polymerlayers to be treated 114 with the plasma drop 106 as the polymer layersare deposited along the path of deposition 112 from the extrusion nozzle110 onto the surface of the substrate 108.

The plasma from the microplasma source 104 may include at least onereactive species, such as a hydroxyl radical or nitrogen oxide radical,that is formed by one or more gases activated within the microplasmasource 104. The gases may include gases naturally present in air, suchas hydrogen, nitrogen, and/or oxygen, for example. If the microplasmasource 104 is in an open configuration that allows gas to pass throughthe microplasma source 104, the gases may be passed through and/orsupplied to the microplasma source 104 and activated. If the microplasmasource 104 is in a closed configuration such that gas is prevented frompassing through the microplasma source 104, the microplasma source 104may ionize gases in an ambient atmosphere of the microplasma source 104to activate the gases in order to form the radical species within theplasma.

A voltage may then be applied to at least one of two electrodespositioned within the microplasma source 104. The applied voltage maycause the plasma drop 106 from the microplasma source 104 to treat 114the surface of the substrate 108 or surface of the deposited polymerlayer with the plasma from the microplasma source 104. The radicalspecies formed within the plasma may oxidize the surface of thesubstrate or the surface of the deposited polymer layer. Surfaceoxidation may increase an interlayer adhesion between the substrate ordeposited polymer layer and a next layer to be deposited from theextrusion nozzle 110.

In some embodiments, two or more microplasma sources may be coupled tothe extrusion nozzle. The microplasma sources may be positioned relativeto the extrusion nozzle such that at least one plasma drop precedes apolymer deposition from an extrusion nozzle in a leading plasmaconfiguration and at least one plasma drop follows a path of polymerdeposition from the extrusion nozzle in a trailing plasma configuration.The microplasma sources may be positioned at a distance, for example,from about 0.5 mm to about 1 mm above the surface of the substrate or asurface of a previously deposited polymer layer dependent on themicroplasma sources position relative to the extrusion nozzle. Forexample, a microplasma source positioned in the trailing plasmaconfiguration may be positioned at a higher height above the surface ofthe substrate than a microplasma source positioned in the leading plasmaconfiguration. In other embodiments, the microplasma source may beseparate from the extrusion nozzle within the printhead.

FIG. 2 illustrates an example comparison of surface adhesion of asubstrate with plasma treatment and a substrate without plasmatreatment, arranged in accordance with at least some embodimentsdescribed herein.

As shown in a diagram 200, a water droplet 202 on a surface of asubstrate 204 may illustrate effects of plasma treatment on surfaceadhesion. In configuration 210, the surface of the substrate 204 has notbeen treated with plasma. In configuration 220, the surface of thesubstrate 204 has been treated with plasma from a microplasma source asdiscussed previously in FIG. 1. As illustrated in configuration 220, thewater droplet 204 has greater surface area contact with the substrate204 than in configuration 210, which may be indicative of increasedsurface adhesion as a result of plasma treatment.

The plasma from the microplasma source used to treat the substrate 204in configuration 220 may include at least one reactive species, such asa hydroxyl radical or nitrogen oxide radical, that is formed by one ormore gases activated within the microplasma source. The one or moregases may include gases naturally present in the air, such as hydrogen,nitrogen, and/or oxygen, for example. The radical species formed withinthe plasma may oxidize the surface of the substrate 204 to increase thesurface adhesion. For example, the radical species may etch a chemistryof the surface to change a chemically inert surface into a polar,oxidized surface, where the polar, oxidized surface may have improvedbonding properties that allow the surface adhesion to increase. Theplasma from the microplasma source may further improve bonding andincrease surface adhesion by cleaning the surface of the substrate 204of absorbed hydrocarbons and oils and physically etching the surface ofthe substrate 204 to create micro-scale roughness, for example.

The plasma within the microplasma source may be a macro-scale dielectricbarrier discharge (DBD), a microhollow plasma, or radio frequency (RF)plasma. A size of the plasma may generally be any size, for example,less than 1 mm² in size, for example. Due to the small size of theplasma drop, the energy needed to create the plasma within themicroplasma source may be optimally focused on the surface of thesubstrate or surface of the deposited polymer layer to be treated. As aresult, the plasma may efficiently oxidize the surface(s) to be treatedat a high rate as the plasma is dropped from the microplasma source,while leaving other regions of a 3D printed article undisturbed.

In some embodiments, the plasma within the microplasma source may bemaintained at a pressure, such as at an atmospheric temperature. Tomaintain the plasma at atmospheric pressure, two high voltage electrodes(a cathode and an anode) positioned at a small distance from one anotherwithin the microplasma source may be implemented. Application of voltageto these electrodes may also cause the plasma drop from the microplasmasource to treat the surface of the substrate or the surface of thedeposited polymer layer, as discussed previously.

FIGS. 3A and 3B illustrate examples of microplasma sources that may becoupled to an extrusion nozzle, arranged in accordance with at leastsome embodiments described herein.

As shown in a diagram 300A of FIG. 3A, the microplasma source may be adielectric barrier discharge (DBD) device 302 configured to produce DBDplasma 304. The DBD device 302 may be fabricated into a silicon chip306, where the silicon chip 306 may serve as a cathode. In the DBDdevice 302, a dielectric layer 310 may separate the silicon chip 306from a sputtered metal layer 312, which may serve as an anode. The DBDdevice 302 may be encapsulated in a silicon nitride layer 308. Due tothe configuration of the DBD device 302, the DBD device 302 may be in aclosed configuration, which may prevent one or more gases from passingthrough the DBD device 302. The DBD device 302 may instead ionize gasespresent in an ambient atmosphere of the DBD device 302 to activate thegases to form a radical species within the DBD plasma. A voltage 314 maythen be applied to the anode, the sputtered metal layer 312 of the DBDdevice 302. The applied voltage 314 may cause a plasma drop of DBDplasma 304 from the DBD device 302 to a surface of a substrate 316 totreat the surface. The reactive species within the DBD plasma 304 maycause oxidation of the treated surface, which may increase interlayeradhesion between the substrate 316 and a next layer of polymer to bedeposited by an extrusion nozzle.

The DBD device 302 may be positioned at a height, such as from about 0.5mm to about 1 mm above the surface of the substrate to prevent directcontact of the DBD device 302 to the surface of the substrate. Theheight may be dependent on how the DBD device 302 is positioned relativeto the extrusion nozzle. For example, the DBD device 302 may bepositioned at a lower height above the surface of the substrate 316 ifthe DBD device 302 is positioned relative to the extrusion nozzle suchthat the DBD plasma 304 drop precedes deposition of a polymer layer fromthe extrusion nozzle. The DBD device 302 may be positioned at a higherheight above the surface of the substrate 316 if the DBD device 302 ispositioned relative to the extrusion nozzle such that the DBD plasma 304drop follows deposition of a polymer layer from the extrusion nozzle.

As shown in a diagram 300B of FIG. 3B, the microplasma source may be analternate configuration of a DBD device 352 configured to produce DBDplasma. The alternate configuration of the DBD device 352 may includetwo or more pieces of metal, such as aluminum (for example, 354 and 356)with one or more perforations 358 drilled through the aluminum. Theperforations 358 may allow the DBD device 352 to be in an openconfiguration, which allows gas to be passed continuously through theDBD device. The aluminum may be anodized to form aluminum oxide on oneor more surfaces of the aluminum pieces after the perforations aredrilled to create the DBD plasma. The open configuration of the DBDdevice 352 may allow gas passing through the perforations 358 toactivate in the DBD device 352 to form a reactive species within the DBDplasma. Upon application of a voltage 360, a plasma drop may treat asurface of a substrate or surface of a deposited polymer layer with theDBD plasma including the reactive species. The reactive species maycause oxidation of the treated surfaces, which may increase interlayeradhesion between the substrate or deposited polymer layer and a nextlayer of polymer to be deposited by the extrusion nozzle.

Similar to the DBD device 302 described previously in the diagram 300Aof FIG. 3A, the DBD device 352 may be positioned at a height, such asabout 0.5 mm to about 1 mm above the surface of the substrate to preventdirect contact of the DBD device 352 to the surface of the substrate.The height may be dependent on how the DBD device 352 is positionedrelative to the extrusion nozzle. For example, the DBD device 352 may bepositioned at a lower height above the surface of the substrate if theDBD device 352 is positioned relative to the extrusion nozzle such thatthe plasma drop precedes deposition of a polymer layer from theextrusion nozzle. The DBD device 352 may be positioned at a higherheight above the surface of the substrate if the DBD device 352 iscoupled in relation to the extrusion nozzle such that the plasma dropfollows deposition of a polymer layer from the extrusion nozzle.

FIG. 4 illustrates another example of a microplasma source that may becoupled to an extrusion nozzle, arranged in accordance with at leastsome embodiments described herein.

As shown in a diagram 400, the microplasma source may be a microhollowplasma source 402 configured to produce microhollow plasma. Themicrohollow plasma source 402 may include an insulating dielectric layer406 formed in between a cathode 408 and an anode 404. The microhollowplasma source 402 may also include one or more perforations 410extending through the cathode 408, dielectric layer 406, and anode 404.The perforations may be formed with a laser following formation of thecathode 408, dielectric layer 406, and anode 404 configuration. Theperforations 410 may allow the microhollow plasma source 402 to be in anopen configuration, which allows one or more gases to be passed and/orsupplied continuously through the microhollow plasma source 402. Thegases may be activated within the microhollow plasma source 402 to format least one reactive species within the microhollow plasma. Uponapplication of a voltage to the anode 404, a plasma drop may treat asurface of a substrate or surface of a deposited polymer layer with themicrohollow plasma including the reactive species. The reactive specieswithin the microhollow plasma may cause oxidation of the treatedsurfaces, which may increase interlayer adhesion between the substrateor deposited polymer layer and a next polymer layer to be deposited formthe extrusion nozzle.

The microhollow plasma produced may have a high density, such as fromabout 10¹⁴ electrons per cubic centimeter (electrons/cc) to about 10¹⁵electrons/cc, and a high temperature, such as from about 1000 Kelvin (K)to about 2000 K, for example. The temperature of the microhollow plasmamay be significantly higher than DBD plasma produced from a DBD devicediscussed previously in FIGS. 3A and 3B, which may be a temperature fromapproximately about 290 K to about 500 K. Although the high temperaturemay be severe for simple surface oxidation, the high density of themicrohollow plasma may be well suited towards transforming organicsurfaces at high sweep rates, and therefore well suited for 3D printing.To make the microhollow plasma more efficient for 3D printing, theeffective temperature may be lowered, for example, by passing roomtemperature gas through the perforations 410 at a rapid rate to lowerthe average gas temperature applied to the surface of the substrate ordeposited polymer layer.

FIG. 5 illustrates an example system to increase interlayer adhesion ofa 3D printed article through employment of an extrusion nozzle coupledto a microplasma source, arranged in accordance with at least someembodiments described herein.

System 500 may include at least one controller 520, at least onedeposition module 522, and at least one treatment module 524. Thecontroller 520 may be operated by human control or may be configured forautomatic operation, or may be directed by a remote controller 550through at least one network (for example, via network 510). Dataassociated with controlling the different processes of production may bestored at and/or received from data stores 560.

The controller 520 may include or control the deposition module 522configured to deposit one or more polymer layers from an extrusionnozzle of a 3D printhead onto a substrate to form a 3D article. Thecontroller 520 may also include or control the treatment module 524configured to treat a surface of the substrate or a surface of thedeposited polymer layers with plasma from a microplasma source coupledto the extrusion nozzle. The plasma may include at least one reactivespecies that may oxidize the treated surfaces to increase interlayeradhesion of the 3D printed article. The surfaces may be treated with aplasma drop, the plasma drop including the at least one reactivespecies, upon application of a voltage to at least one of two electrodespositioned within the microplasma source causing the plasma drop fromthe microplasma source.

As discussed previously, the microplasma source may be coupled to theextrusion nozzle. The microplasma source may be positioned relative tothe extrusion nozzle such that the plasma drop from the microplasmasource precedes a path of polymer deposition from the extrusion nozzlein a leading plasma configuration or follows a path of polymerdeposition from the extrusion nozzle in a trailing plasma configuration.If the microplasma source is positioned in the leading plasmaconfiguration, the surface of the substrate may be treated to increaseinterlayer adhesion. If the microplasma source is positioned in thetrailing plasma configuration, the surface of the previously depositedpolymer layers may be treated to increase interlayer adhesion.

The examples in FIGS. 1 through 5 have been described using specificapparatuses, configurations, and systems to increase interlayer adhesionof a 3D printed article through employment of an extrusion nozzlecoupled to a microplasma source. Embodiments to increase interlayeradhesion of a 3D printed article are not limited to the specificapparatuses, configurations, and systems according to these examples.

FIG. 6 illustrates a general purpose computing device, which may be usedto facilitate an increase of interlayer adhesion of a 3D printed articlethrough employment of an extrusion nozzle coupled to a microplasmasource, arranged in accordance with at least some embodiments describedherein.

For example, the computing device 600 may be used as a server, desktopcomputer, portable computer, smart phone, special purpose computer, orsimilar device such as a controller, a new component, a cluster ofexisting components in an operational system including a vehicle and asmart dwelling. In an example basic configuration 602, the computingdevice 600 may include one or more processors 604 and a system memory606. A memory bus 608 may be used for communicating between theprocessor 604 and the system memory 606. The basic configuration 602 isillustrated in FIG. 6 by those components within the inner dashed line.

Depending on the desired configuration, the processor 604 may be of anytype, including but not limited to a microprocessor (μP), amicrocontroller (μC), a digital signal processor (DSP), or anycombination thereof. The processor 604 may include one more levels ofcaching, such as a level cache memory 612, one or more processor cores614, and registers 616. The example processor cores 614 may (each)include an arithmetic logic unit (ALU), a floating point unit (FPU), adigital signal processing core (DSP Core), or any combination thereof.An example memory controller 618 may also be used with the processor604, or in some implementations the memory controller 618 may be aninternal part of the processor 604.

Depending on the desired configuration, the system memory 606 may be ofany type including but not limited to volatile memory (such as RAM),non-volatile memory (such as ROM, flash memory, etc.) or any combinationthereof. The system memory 606 may include an operating system 620, anapplication 622, and program data 624. The application 622 may include adeposition module 626 and a treatment module 627, which may be anintegral part of the application or a separate application on its own.The deposition module 626 may be configured to deposit one or morepolymer layers from an extrusion nozzle of a 3D printhead onto asubstrate to form a 3D article. The treatment module 627 may beconfigured to treat a surface of the substrate or a surface of thedeposited polymer layers with plasma from a microplasma source coupledto the extrusion nozzle. The program data 624 may include, among otherdata, process data 628 related to deposition and treatment, as describedherein.

The computing device 600 may have additional features or functionality,and additional interfaces to facilitate communications between the basicconfiguration 602 and any desired devices and interfaces. For example, abus/interface controller 630 may be used to facilitate communicationsbetween the basic configuration 602 and one or more data storage devices632 via a storage interface bus 634. The data storage devices 632 may beone or more removable storage devices 636, one or more non-removablestorage devices 638, or a combination thereof. Examples of the removablestorage and the non-removable storage devices include magnetic diskdevices such as flexible disk drives and hard-disk drives (HDD), opticaldisk drives such as compact disk (CD) drives or digital versatile disk(DVD) drives, solid state drives (SSD), and tape drives to name a few.Example computer storage media may include volatile and nonvolatile,removable and non-removable media implemented in any method ortechnology for storage of information, such as computer readableinstructions, data structures, program modules, or other data.

The system memory 606, the removable storage devices 636 and thenon-removable storage devices 638 are examples of computer storagemedia. Computer storage media includes, but is not limited to, RAM, ROM,EEPROM, flash memory or other memory technology, CD-ROM, digitalversatile disks (DVD), solid state drives, or other optical storage,magnetic cassettes, magnetic tape, magnetic disk storage or othermagnetic storage devices, or any other medium which may be used to storethe desired information and which may be accessed by the computingdevice 600. Any such computer storage media may be part of the computingdevice 600.

The computing device 600 may also include an interface bus 640 forfacilitating communication from various interface devices (for example,one or more output devices 642, one or more peripheral interfaces 644,and one or more communication devices 646) to the basic configuration602 via the bus/interface controller 630. Some of the example outputdevices 642 include a graphics processing unit 648 and an audioprocessing unit 650, which may be configured to communicate to variousexternal devices such as a display or speakers via one or more A/V ports652. One or more example peripheral interfaces 644 may include a serialinterface controller 654 or a parallel interface controller 656, whichmay be configured to communicate with external devices such as inputdevices (for example, keyboard, mouse, pen, voice input device, touchinput device, etc.) or other peripheral devices (for example, printer,scanner, etc.) via one or more I/O ports 658. An example communicationdevice 646 includes a network controller 660, which may be arranged tofacilitate communications with one or more other computing devices 662over a network communication link via one or more communication ports664. The one or more other computing devices 662 may include servers,client devices, and comparable devices.

The network communication link may be one example of a communicationmedia. Communication media may typically be embodied by computerreadable instructions, data structures, program modules, or other datain a modulated data signal, such as a carrier wave or other transportmechanism, and may include any information delivery media. A “modulateddata signal” may be a signal that has one or more of its characteristicsset or changed in such a manner as to encode information in the signal.By way of example, and not limitation, communication media may includewired media such as a wired network or direct-wired connection, andwireless media such as acoustic, radio frequency (RF), microwave,infrared (IR) and other wireless media. The term computer readable mediaas used herein may include both storage media and communication media.

The computing device 600 may be implemented as a part of a generalpurpose or specialized server, mainframe, or similar computer thatincludes any of the above functions. The computing device 600 may alsobe implemented as a personal computer including both laptop computer andnon-laptop computer configurations.

Example embodiments may also include a printhead with at least oneextrusion nozzle coupled to a microplasma source employed in a 3Dprinting system to increase interlayer adhesion of a 3D printed article.These methods can be implemented in any number of ways, including thestructures described herein. One such way may be by machine operations,of devices of the type described in the present disclosure. Anotheroptional way may be for one or more of the individual operations of themethods to be performed in conjunction with one or more human operatorsperforming some of the operations while other operations may beperformed by machines. These human operators need not be collocated witheach other, but each can be only with a machine that performs a portionof the program. In other embodiments, the human interaction can beautomated such as by pre-selected criteria that may be machineautomated.

FIG. 7 is a flow diagram illustrating an example method to increaseinterlayer adhesion of a 3D printed article through employment of atleast one extrusion nozzle coupled to a microplasma source that may beperformed by a computing device such as the computing device in FIG. 6,arranged in accordance with at least some embodiments described herein.

Example methods may include one or more operations, functions or actionsas illustrated by one or more of blocks 722 and/or 724. The operationsdescribed in the blocks 722 through 724 may also be stored ascomputer-executable instructions in a computer-readable medium such as acomputer-readable medium 720 of a computing device 710.

An example process to increase interlayer adhesion of a 3D printedarticle may begin with block 722, “DEPOSIT ONE OR MORE POLYMER LAYERSFROM AN EXTRUSION NOZZLE INTEGRATED WITH A MICROPLASMA SOURCE ONTO ASUBSTRATE TO FORM A 3D PRINTED ARTICLE,” where a deposition module maybe configured to deposit one or more polymer layers from an extrusionnozzle onto a substrate to form a 3D printed article. The extrusionnozzle may be coupled to a microplasma source, where the microplasmasource may be positioned relative to the extrusion nozzle such that aplasma drop for the microplasma source may precede or follow a path ofpolymer deposition from the extrusion nozzle.

Block 722 may be followed by block 724, “TREAT A SURFACE OF THESUBSTRATE OR A SURFACE OF THE ONE OR MORE DEPOSITED POLYMER LAYERS WITHPLASMA FROM THE MICROPLASMA SOURCE,” where a treatment module may beconfigured to treat a surface of the substrate or a surface of depositedpolymer layers with plasma from the microplasma source dependent on theposition of the microplasma source relative to the extrusion nozzle. Forexample, if the microplasma source is positioned relative to theextrusion nozzle such that the plasma drop from the microplasma sourceprecedes the path of polymer deposition in a leading plasmaconfiguration, the surface of the substrate may be treated. If themicroplasma source is positioned relative to the extrusion nozzle suchthat the plasma drop from the microplasma source follows the path ofpolymer deposition in a trailing plasma configuration, the surface ofthe previously deposited polymer layers may be treated. The surface ofthe substrate or the surface of deposited polymer layers may be treatedupon application of a voltage to at least one of two electrodespositioned within the microplasma source causing a plasma drop from themicroplasma source. The plasma may include a reactive species formedwithin the microplasma source, where the reactive species oxidizes thesurface of the substrate or the surface of deposited polymer layers,which may increase interlayer adhesion.

The blocks included in the above described process are for illustrationpurposes. Employment of an extrusion nozzle coupled to a microplasmasource in a 3D printing system to increase interlayer adhesion of a 3Dprinted article may be implemented by similar processes with fewer oradditional blocks. In some embodiments, the blocks may be performed in adifferent order. In some other embodiments, various blocks may beeliminated. In still other embodiments, various blocks may be dividedinto additional blocks, or combined together into fewer blocks.

FIG. 8 illustrates a block diagram of an example computer programproduct, arranged in accordance with at least some embodiments describedherein.

In some embodiments, as shown in FIG. 8, the computer program product800 may include a signal bearing medium 802 that may also include one ormore machine readable instructions 804 that, when executed by, forexample, a processor, may provide the functionality described herein.Thus, for example, referring to the processor 604 in FIG. 6, adeposition module 626 and a treatment module 627 executed on theprocessor 604 may undertake one or more of the tasks shown in FIG. 8 inresponse to the instructions 804 conveyed to the processor 604 by themedium 802 to perform actions associated with increasing interlayeradhesion of a 3D printed article as described herein. Some of thoseinstructions may include, for example, one or more instructions todeposit one or more polymer layers from an extrusion nozzle integratedwith a microplasma source onto a substrate to form a 3D printed article,and treat a surface of the substrate or a surface of the one or moredeposited polymer layers with plasma from the microplasma source,according to some embodiments described herein.

In some implementations, the signal bearing medium 802 depicted in FIG.8 may encompass a computer-readable medium 806, such as, but not limitedto, a hard disk drive, a solid state drive, a Compact Disc (CD), aDigital Versatile Disk (DVD), a digital tape, memory, etc. In someimplementations, the signal bearing medium 802 may encompass arecordable medium 808, such as, but not limited to, memory, read/write(R/W) CDs, R/W DVDs, etc. In some implementations, the signal bearingmedium 802 may encompass a communications medium 810, such as, but notlimited to, a digital and/or an analog communication medium (forexample, a fiber optic cable, a waveguide, a wired communications link,a wireless communication link, etc.). Thus, for example, the programproduct 800 may be conveyed to one or more modules of the processor 604of FIG. 6 by an RF signal bearing medium, where the signal bearingmedium 802 is conveyed by the wireless communications medium 810 (forexample, a wireless communications medium conforming with the IEEE802.11 standard).

According to some embodiments, methods are described to increaseinterlayer adhesion of a 3D printed article. An example method mayinclude depositing a polymer layer from an extrusion nozzle of a 3Dprinter onto a substrate to form the 3D printed article, where theextrusion nozzle is coupled to a microplasma source. The example methodmay also include treating a surface of the substrate or a surface of thedeposited polymer layer with plasma from the microplasma source.

In other embodiments, one or more gases may be supplied to themicroplasma source, where the one or more gases may be activated to format least one reactive species in the plasma that oxidizes the surface ofthe substrate or the surface of the deposited polymer layer to increasean interlayer adhesion. A voltage may be applied to cause a plasma dropfrom the microplasma source onto the surface of the substrate or thesurface of the deposited polymer layer to treat the surface of thesubstrate or the surface of the deposited polymer layer with the plasmafrom the microplasma source. The microplasma source may be positioned inrelation to the extrusion nozzle such that the plasma drop precedes orfollows a path of a polymer deposition from the extrusion nozzle. Theplasma drop from the microplasma source may be caused onto a surface ofa previously deposited polymer layer prior to a deposition of anotherpolymer layer.

In further embodiments, the microplasma source may be positioned at adistance, such as from about 0.5 mm to about 1 mm above the surface ofthe substrate or the surface of the deposited polymer layer. Theextrusion nozzle may be rotated as the polymer layer is deposited totrack changes in a polymer deposition. The microplasma source may beincorporated into the extrusion nozzle to allow treatment of the polymerlayer with the plasma as the polymer layer is deposited from theextrusion nozzle.

According to some examples, printheads may be described. An exampleprinthead may include an extrusion nozzle configured to deposit one ormore polymer layers onto a substrate to form a 3D printed article. Theexample printhead may also include a microplasma source coupled to theextrusion nozzle, the microplasma source being configured to treat asurface of the substrate or a surface of the deposited polymer layerwith plasma from the microplasma source.

In other examples, the example printhead may further include two or moreelectrodes configured to apply a voltage to cause a plasma drop from themicroplasma source onto the surface of the substrate or the surface ofeach polymer layer in order to oxidize the surface of the substrate orthe surface of each polymer layer, where the two or more electrodes maybe positioned within the microplasma source. The microplasma source maybe positioned in relation to the extrusion nozzle such that the plasmadrop precedes or follows a path of the extrusion nozzle. A surface areaof the plasma drop may be arranged to be less than about 1 mm² in size.Oxidization of the surface of the substrate or the surface of eachpolymer layer may increase interlayer adhesion of a 3D printed article.

In further examples, the plasma within the microplasma source may be amacro-scale dielectric barrier discharge (DBD) plasma, a microhollowplasma, or radio frequency (RF) plasma, and the plasma may be maintainedat atmospheric pressure. The microplasma source comprising DBD plasmamay be composed of one or more silicon chips or two or more pieces ofperforated aluminum. The microplasma source may be configured to depositplasma with at least one reactive species to treat the surface of thesubstrate or the surface of the deposited polymer layer. One or moregases may be configured to pass through the microplasma source in anopen configuration to allow activation of the one or more gases to formthe at least one reactive species. The microplasma source may beconfigured to ionize one or more gases present in the microplasma sourcein a closed configuration to allow activation of the one or more gasesto form the at least one reactive species, where the at least onereactive species include a hydroxyl radical or nitrogen oxide radical.

According to some embodiments, systems for increasing interlayeradhesion of a 3D printed article are described. An example system mayinclude a deposition module that includes an extrusion nozzle and isconfigured to deposit one or more polymer layers from the extrusionnozzle onto a substrate to form a 3D printed article. The example systemmay also include a treatment module including a microplasma sourcecoupled to the extrusion nozzle and configured to treat a surface of thesubstrate or a surface of the one or more deposited polymer layers withplasma from the microplasma source. The example system may furtherinclude a controller configured to coordinate operations of thedeposition module and the treatment module during a fabrication of the3D printed article.

In other embodiments, the treatment module may be configured to treatthe surface of the substrate or the surface of the one or more depositedpolymer layers with plasma from the microplasma source in response to anapplication of a voltage by two or more electrodes causing a plasma dropfrom the microplasma source. The treatment module may include two ormore microplasma sources coupled to the extrusion nozzle, where the twoor more microplasma sources may be positioned in relation to theextrusion nozzle such that at least two plasma drops precede and followa path of polymer deposition from the extrusion nozzle.

In further embodiments, the two or more microplasma sources may befurther positioned at a distance, such as from about 0.5 mm to about 1mm above the surface of the substrate or a surface of a previouslydeposited polymer layer. One of the two or more microplasma sources maybe positioned higher above the surface of the substrate or the surfaceof the previously deposited polymer layer than another one of the two ormore microplasma sources in relation to the surface of the substratesuch that one of the at least two plasma drops precedes the path ofpolymer deposition. The microplasma source may be positioned separatelyfrom the extrusion nozzle.

According to some examples, a computer-readable storage medium withinstructions stored thereon to increase interlayer adhesion of a 3Dprinted article may be described. The instructions may cause a methodsimilar to the methods provided above to be performed when executed.

EXAMPLES

Following are illustrative examples of how some embodiments may beimplemented, and are not intended to limit the scope of embodiments inany way.

Example 1 An Extrusion Nozzle Coupled to a Dielectric Barrier Discharge(DBD) Microplasma Source Fabricated into a Silicon Chin

An extrusion nozzle may be coupled to a DBD device fabricated into asilicon chip. The DBD device may include a dielectric polyimide layerthat separates the silicon chip from a sputtered Nickel layer. Thepolyimide layer and sputtered Nickel layer may further be encapsulatedin a silicon nitride layer. The silicon chip may serve as a cathode andthe sputtered Nickel layer may serve as the anode. The DBD device may becoupled to an extrusion nozzle such that a plasma drop from the DBDdevice precedes deposition of a polymer layer from the extrusion nozzlein a leading plasma configuration. As a result, the DBD device ispositioned 0.5 mm above a surface of a substrate to prevent directcontact of the DBD device to the surface of the substrate.

Once positioned, the DBD device may be run in an alternating current(AC) mode with ±250 Volts (V) power at a frequency of 10 kiloHertz(kHz). The current may cause a plasma drop from the DBD device to thesurface of the substrate to treat the surface of the substrate with DBDplasma. The plasma may be at a room temperature of approximately 290 Kand may modify the surface of the substrate in less than 2 seconds.Hydroxyl radicals within the DBD plasma formed by activation of hydrogengas in an ambient atmosphere of the DBD device may cause the surface ofthe substrate to oxidize, which may increase interlayer adhesion betweenthe substrate and a next layer of polymer to be deposited by theextrusion nozzle.

Example 2 An Extrusion Nozzle Coupled to a DBD Microplasma SourceFabricated from Two or More Pieces of Aluminum

An extrusion nozzle may be coupled to a DBD device fabricated from twoaluminum foils, each 70 micrometers thick, with one or more perforationsextending through the thickness of the aluminum foils to allow an openconfiguration. The aluminum foils may be anodized to a depth of 10micrometers to form aluminum oxide on one or more surfaces of thealuminum foils. The DBD device may be coupled to an extrusion nozzlesuch that a plasma drop from the DBD device follows deposition of apolymer layer from the extrusion nozzle in a trailing plasmaconfiguration. As a result, the DBD device is positioned 1.0 mm above asurface of a deposited polymer layer to prevent direct contact of theDBD device to the surface of the deposited polymer layer.

Once positioned, the DBD device may be run in a 5-50 kV AC sweep at 275V power to form the DBD plasma, and the open configuration may allow amix of nitrogen and hydrogen gas passing through the perforations toactivate in the DBD device 352 to form nitrogen oxide radicals withinthe DBD plasma. Upon application of the voltage, a plasma drop may treatthe surface of the deposited polymer layer with the DBD plasma includingthe nitrogen oxide radicals. The nitrogen oxide radicals may causeoxidation of the treated surfaces, which may increase interlayeradhesion between the deposited polymer layer and a next layer of polymerto be deposited by the extrusion nozzle.

Example 3 An Extrusion Nozzle Integrated with Two Microhollow PlasmaSources

The extrusion nozzle may be coupled to two microhollow plasma sourcesthat each include a dielectric layer of alumina formed in between twolayers of molybdenum, where one layer of the molybdenum serves as acathode and the other serves as an anode. The microhollow plasma sourcesmay also include perforations formed with a laser, where theperforations may extend through the molybdenum and alumina layers toallow an open configuration and may be approximately 1000 micrometers indiameter. The open configuration may allow air to be passed and/orsupplied continuously through the microhollow plasma source. Hydrogen,nitrogen, and oxygen gases within the air may be activated within themicrohollow plasma sources to form hydroxyl radicals and nitrogen oxideradicals within the plasma.

The first microhollow plasma source may be coupled to the extrusionnozzle such that a plasma drop from the microhollow plasma precedesdeposition of a polymer layer from the extrusion nozzle in a leadingplasma configuration. As a result, the microhollow plasma is positionedabout 0.5 mm above a surface of a substrate to prevent direct contact ofthe microhollow plasma to the surface of the substrate. Upon applicationof a 1-10 milliAmps (mA) current to the other molybdenum layer servingas the anode, a plasma drop may treat a surface of a substrate with themicrohollow plasma, the plasma including the hydroxyl radicals andnitrogen oxide radicals. The microhollow plasma produced may include ahigh density and a high temperature, from 1000-2000 Kelvin (K), forexample. The radicals may cause oxidation of the surface of thesubstrate, which may increase interlayer adhesion between the substrateand a polymer layer to be deposited by the extrusion nozzle.

The second microhollow plasma source may be coupled to the extrusionnozzle such that a plasma drop from the microhollow plasma followsdeposition of a polymer layer from the extrusion nozzle in a trailingplasma configuration. As a result, the microhollow plasma may bepositioned about 1.0 mm above a surface of a substrate to prevent directcontact of the microhollow plasma to a surface of a deposited polymerlayer. Upon application of a 1-10 mA current to the other molybdenumlayer serving as the anode, a plasma drop may treat the surface of thedeposited polymer layer with the microhollow plasma including thehydroxyl radicals and nitrogen oxide radicals, where the radicals maycause oxidation of the surface of the deposited polymer layer. Oxidationof the surface may increase interlayer adhesion between the depositedpolymer layer and a next polymer layer to be deposited by the extrusionnozzle.

There are various vehicles by which processes and/or systems and/orother technologies described herein may be effected (for example,hardware, software, and/or firmware), and that the preferred vehiclewill vary with the context in which the processes and/or systems and/orother technologies are deployed. For example, if an implementerdetermines that speed and accuracy are paramount, the implementer mayopt for a mainly hardware and/or firmware vehicle; if flexibility isparamount, the implementer may opt for a mainly software implementation;or, yet again alternatively, the implementer may opt for somecombination of hardware, software, and/or firmware.

While various compositions, methods, systems, and devices are describedin terms of “comprising” various components or steps (interpreted asmeaning “including, but not limited to”), the compositions, methods,systems, and devices can also “consist essentially of” or “consist of”the various components and steps, and such terminology should beinterpreted as defining essentially closed-member groups.”

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, each functionand/or operation within such block diagrams, flowcharts, or examples maybe implemented, individually and/or collectively, by a wide range ofhardware, software, firmware, or virtually any combination thereof. Inone embodiment, several portions of the subject matter described hereinmay be implemented via Application Specific Integrated Circuits (ASICs),Field Programmable Gate Arrays (FPGAs), digital signal processors(DSPs), or other integrated formats. However, some aspects of theembodiments disclosed herein, in whole or in part, may be equivalentlyimplemented in integrated circuits, as one or more computer programsrunning on one or more computers (for example, as one or more programsrunning on one or more computer systems), as one or more programsrunning on one or more processors (for example as one or more programsrunning on one or more microprocessors), as firmware, or as virtuallyany combination thereof, and that designing the circuitry and/or writingthe code for the software and or firmware would be possible in light ofthis disclosure.

The present disclosure is not to be limited in terms of the particularembodiments described in this application, which are intended asillustrations of various aspects. Many modifications and variations canbe made without departing from its spirit and scope Functionallyequivalent methods and apparatuses within the scope of the disclosure,in addition to those enumerated herein, will be possible from theforegoing descriptions. Such modifications and variations are intendedto fall within the scope of the appended claims. The present disclosureis to be limited only by the terms of the appended claims, along withthe full scope of equivalents to which such claims are entitled. It isto be understood that this disclosure is not limited to particularmethods, systems, or components, which can, of course, vary. It is alsoto be understood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to belimiting.

In addition, the mechanisms of the subject matter described herein arecapable of being distributed as a program product in a variety of forms,and that an illustrative embodiment of the subject matter describedherein applies regardless of the particular type of signal bearingmedium used to actually carry out the distribution. Examples of a signalbearing medium include, but are not limited to, the following: arecordable type medium such as a floppy disk, a hard disk drive, aCompact Disc (CD), a Digital Versatile Disk (DVD), a digital tape, acomputer memory, etc.; and a transmission type medium such as a digitaland/or an analog communication medium (for example, a fiber optic cable,a waveguide, a wired communications link, a wireless communication link,etc.).

Those skilled in the art will recognize that it is common within the artto describe devices and/or processes in the fashion set forth herein,and thereafter use engineering practices to integrate such describeddevices and/or processes into data processing systems. That is, at leasta portion of the devices and/or processes described herein may beintegrated into a data processing system via a reasonable amount ofexperimentation. Those having skill in the art will recognize that atypical data processing system generally includes one or more of asystem unit housing, a video display device, a memory such as volatileand non-volatile memory, processors such as microprocessors and digitalsignal processors, computational entities such as operating systems,drivers, graphical user interfaces, and applications programs, one ormore interaction devices, such as a touch pad or screen, and/or controlsystems including feedback loops.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely exemplary, and that in fact many other architectures may beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that particular functionality is achieved.Hence, any two components herein combined to achieve a particularfunctionality may be seen as “associated with” each other such that theparticular functionality is achieved, irrespective of architectures orintermediate components. Likewise, any two components so associated mayalso be viewed as being “operably connected”, or “operably coupled”, toeach other to achieve the particular functionality, and any twocomponents capable of being so associated may also be viewed as being“operably couplable”, to each other to achieve the particularfunctionality. Specific examples of operably couplable include but arenot limited to physically connectable and/or physically interactingcomponents and/or wirelessly interactable and/or wirelessly interactingcomponents and/or logically interacting and/or logically interactablecomponents.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations may be expressly set forth herein for sakeof clarity.

It will be understood by those within the art that, in general, termsused herein, and especially in the appended claims (for example, bodiesof the appended claims) are generally intended as “open” terms (forexample, the term “including” should be interpreted as “including butnot limited to,” the term “having” should be interpreted as “having atleast,” the term “includes” should be interpreted as “includes but isnot limited to,” etc.). It will be further understood by those withinthe art that if a specific number of an introduced claim recitation isintended, such an intent will be explicitly recited in the claim, and inthe absence of such recitation no such intent is present. For example,as an aid to understanding, the following appended claims may containusage of the introductory phrases “at least one” and “one or more” tointroduce claim recitations. However, the use of such phrases should notbe construed to imply that the introduction of a claim recitation by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (for example, “a” and/or “an” should be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould be interpreted to mean at least the recited number (for example,the bare recitation of “two recitations,” without other modifiers, meansat least two recitations, or two or more recitations).

Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” is used, in general such a constructionis intended in the sense one having skill in the art would understandthe convention (for example, “a system having at least one of A, B, andC” would include but not be limited to systems that have A alone, Balone, C alone, A and B together, A and C together, B and C together,and/or A, B, and C together, etc.). It will be further understood bythose within the art that virtually any disjunctive word and/or phrasepresenting two or more alternative terms, whether in the description,claims, or drawings, should be understood to contemplate thepossibilities of including one of the terms, either of the terms, orboth terms. For example, the phrase “A or B” will be understood toinclude the possibilities of “A” or “B” or “A and B.”

As will be understood by one skilled in the art, for any and allpurposes, such as in terms of providing a written description, allranges disclosed herein also encompass any and all possible subrangesand combinations of subranges thereof. Any listed range can be easilyrecognized as sufficiently describing and enabling the same range beingbroken down into at least equal halves, thirds, quarters, fifths,tenths, etc. As a non-limiting example, each range discussed herein canbe readily broken down into a lower third, middle third and upper third,etc. As will also be understood by one skilled in the art all languagesuch as “up to,” “at least,” “greater than,” “less than,” and the likeinclude the number recited and refer to ranges which can be subsequentlybroken down into subranges as discussed above. Finally, as will beunderstood by one skilled in the art, a range includes each individualmember. Thus, for example, a group having 1-3 cells refers to groupshaving 1, 2, or 3 cells. Similarly, a group having 1-5 cells refers togroups having 1, 2, 3, 4, or 5 cells, and so forth.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are possible. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting, with the true scope and spirit beingindicated by the following claims.

1. A method to increase interlayer adhesion of a three-dimensional (3D)printed article, the method comprising: positioning an extrusion nozzleof a 3D printer along a path; coupling a microplasma source to theextrusion nozzle such that the microplasma source is positioned alongthe path of the extrusion nozzle, wherein the microplasma source ispositioned to either precede or follow the extrusion nozzle along thepath; depositing a polymer layer from the extrusion nozzle along thepath onto a surface of a substrate to form the 3D printed article; andtreating the surface of the substrate or a surface of the depositedpolymer layer with plasma from the microplasma source by applying avoltage between a ground reference and at least one of two electrodespositioned within the microplasma source to cause a plasma drop from themicroplasma source onto the surface of the substrate or the surface ofthe deposited polymer layer.
 2. The method of claim 1, furthercomprising: supplying one or more gases to the microplasma source,wherein the one or more gases are activated to form at least onereactive species in the plasma that oxidizes the surface of thesubstrate or the surface of the deposited polymer layer to increase aninterlayer adhesion. 3.-4. (canceled)
 5. The method of claim 1, whereintreating the surface of the substrate or the surface of the depositedpolymer layer with plasma from the microplasma source comprises:applying the voltage between the ground reference and the at least oneof two electrodes positioned within the microplasma source to cause theplasma drop from the microplasma source onto a surface of a previouslydeposited polymer layer prior to a deposition of another polymer layer.6. The method of claim 1, further comprising: positioning themicroplasma source from about 0.5 mm to about 1 mm above the surface ofthe substrate or the surface of the deposited polymer layer.
 7. Themethod of claim 1, further comprising: rotating the extrusion nozzle asthe polymer layer is deposited to track changes in a polymer deposition.8. The method of claim 1, further comprising: incorporating themicroplasma source into the extrusion nozzle to allow treatment of thepolymer layer with the plasma as the polymer layer is deposited from theextrusion nozzle.
 9. A printhead, comprising: an extrusion nozzle of athree-dimensional (3D) printer configured to deposit one or more polymerlayers onto a surface of a substrate to form a 3D printed article; and amicroplasma source incorporated into the extrusion nozzle, themicroplasma source configured to treat a surface of the substrate or asurface of a deposited polymer layer with plasma from the microplasmasource as the one or more polymer layers are deposited from theextrusion nozzle.
 10. The printhead of claim 9, further comprising twoor more electrodes positioned within the microplasma source, wherein themicroplasma source is configured to apply a voltage between a groundreference and at least one of the two or more electrodes to cause aplasma drop to be deposited from the microplasma source onto the surfaceof the substrate or the surface of each polymer layer. 11.-14.(canceled)
 15. The printhead of claim 9, wherein the microplasma sourceis a macro-scale dielectric barrier discharge (DBD) source, amicrohollow plasma source, or a radio frequency (RF) plasma source. 16.(canceled)
 17. The printhead of claim 15, wherein the microplasma sourceis composed of one or more silicon chips or two or more mated pieces ofperforated aluminum.
 18. The printhead of claim 9, wherein themicroplasma source is configured to deposit plasma to the surface of thesubstrate or the surface of the deposited polymer layer with plasma thatcomprises at least one reactive species.
 19. The printhead of claim 18,further comprising: a gas source coupled to the microplasma source,wherein the microplasma source is further configured to pass through oneor more gases received from the gas source in an open configuration toallow activation of the one or more gases to form the at least onereactive species.
 20. The printhead of claim 18, further comprising: agas source coupled to the microplasma source, wherein the microplasmasource is further configured to ionize one or more gases received fromthe gas source in a closed configuration to allow activation of the oneor more gases to form the at least one reactive species.
 21. Theprinthead of claim 18, wherein the at least one reactive species includea hydroxyl radical or nitrogen oxide radical.
 22. A system to increaseinterlayer adhesion of a three-dimensional (3D) printed article, thesystem comprising: a deposition module comprising an extrusion nozzle ofa 3D printer positioned along a path, the deposition module configuredto deposit one or more polymer layers from the extrusion nozzle alongthe path onto a surface of a substrate to form a 3D printed article; atreatment module comprising two or more microplasma sources coupled tothe extrusion nozzle and positioned along the path of the extrusionnozzle such that a first of the two or more microplasma sources precedesthe extrusion nozzle and a second of the two or more microplasma sourcesfollows the extrusion nozzle, the treatment module configured to treat asurface of the substrate or a surface of the one or more depositedpolymer layers with plasma from the two or more microplasma sources; anda controller configured to coordinate operations of the depositionmodule and the treatment module during a fabrication of the 3D printedarticle.
 23. The system of claim 22, wherein the treatment modulefurther comprises two or more electrodes positioned within each of thetwo or more microplasma sources, wherein each of the two or moremicroplasma sources is configured to apply a voltage between a groundreference and at least one of the two or more electrodes to cause aplasma drop to be deposited from each of the two or more microplasmasources onto the surface of the substrate or the surface of the one ormore deposited polymer layers.
 24. (canceled)
 25. The system of claim23, wherein plasma drop deposited from the first of the two or moremicroplasma sources precedes a path of polymer deposition from theextrusion nozzle and a plasma drop deposited from the second of the twoor more microplasma sources follows a path of polymer deposition fromthe extrusion nozzle.
 26. The system of claim 22, wherein the two ormore microplasma sources are further positioned from about 0.5 mm toabout 1 mm above the surface of the substrate or a surface of apreviously deposited polymer layer.
 27. The system of claim 26, whereinthe first of the two or more microplasma sources that precedes theextrusion nozzle is positioned higher above the surface of the substrateor the surface of the previously deposited polymer layer relative to thesecond of the two or more microplasma sources follows the extrusionnozzle.
 28. The system of claim 22, wherein the two or more microplasmasource are positioned separately from the extrusion nozzle. 29.(canceled)